Treatment of coated fabrics



Patented. Jan. 31, 1939 UNITED STATES PATENT OFFICE TREATMENT OF COATED FABRICS No Drawing. Application December 13, 1935, Serial No. 54,263

1 Claim.

This invention relates to coated fabrics, and particularly to a process for treating fabrics which have been coated so that the coated materials will not shrink to an undesirable extent when they are alternately subjected to'moisture and drying.

The shrinkage of fabric from alternate wetting and drying is one of the commonest faults of both coated and uncoated fabric materials. Although considerable advancement has been made in overcoming this defect by various methods whereby uncoated materials are preshrunk and excellent results have been obtained, the processes heretofore devised are so costly to operate that they are not practical for the treatment of base materials which are to be coated if low cost and relatively low shrinkage of the finished materials are desired. Furthermore, the preshrunk materials heretofore made have not given the best results when they were coated because the fabrics were easily stretched under tension and they were subjected to more or less stretching during the coating operations, particularly in the direction of the warp. The effect of preshrinkage of the uncoated material was furthermore partially millified by repeated heat treatments which were essential in manufacturing the coated materials, thus the necessary stretching or heating or both the stretching and the heating during the coating operations destroyed much, if not all of the advantage gained by the prior art methods of treatment so that when the coated material was subjected to alternate wetting and drying in service, a harmful shrinkage resulted. Therefore, it is desirable to provide means for reducing the above defects to a harmless degree or causing them to be eliminated.

It is among the objects of this invention to provide methods of treating coated fabrics to reduce shrinkage of the fabric base to a minimum when the coated material is subjected to conditions which cause shrinkage.

Other objects of the invention will be apparent in connection with the description thereof,

The objects of the invention are accomplished generally by subjecting the coated fabric to a complete wetting so that the fabric base becomes thoroughly saturated with moisture and then removing the moisture by drying the fabric under substantially little or no tension. In cases where it is necessary or desirable, theprocess is repeated.

The following description of a preferred embodiment of the invention is illustrative. A suitable fabric such as a sheeting weave cotton fabric weighing about 2.28 ounces per linear yard 40 inches in width and having a yarn count of 96 in the warp direction and 100 in the filler direction is coated on one side by any suitable means well known in the art. A plurality of coatings are usually applied and a composition of the following approximate formulation may be used:

Per cent by weight Cellulose nitrate 15.00 Pigment 22.30 Softener 11.10 Ethyl acetate 20.64 Denatured ethyl alcohol 30.96

The volatile material of the coating composition is removed by suitable means, such as passing over heated coils or thru a heated chamber subsequent to the application of each coating and before the application of additional coatings.

After the desired amount of coating composition has been applied the coated material is immersed in warm water in such a manner as to completely saturate the woven fabric. A suitable apparatus for this purpose is a standard dye jig although other means which does not stretch the material may be used. The wetted coated fabric is loosely rolled and allowed to stand loosely rolled in this wet condition for approximately four hours. After this time the material is dried at room temperature or elevated temperature by festooning or some other means whereby substantially little or no tension is applied to the coated fabric during the drying process.

This wetting and drying operation may be repeated until the material reaches the degree of non-shrinkability desired for the particular use to which the material is to be applied. For comparatively light weight coated sheeting fabrics, one treatment may be suflicient. For heavier fabrics the process may have to be repeated a number of times to produce the desired result.

Untreated light weight coated sheetings will normally shrink from 1 to 1.5%. When in service and subjected to conditions conducive to shrinkage, the shrinkage of materials which have been treated in accordance with the above description is practically negligible, say 0.3% to approximately 0.5%.. Such a reduction in tendency to shrinkage is satisfactory for most uses to which the coated fabric is applied.

The invention can be applied to double coated fabrics as well as to single coated fabrics but in the treatment of double coated fabrics, the coating on at least one side is desirably limited so that some of the nap can act as a wick or will be uncovered to an extent such that it can be wetted to carry the water or other shrinkage material into the fabric between the coatings. For example, light weight sheetings carrying a coating of. about 0.3 to 1.5 ounces of a cellulose derivative per square yard will permit water to penetrate into the fabric by way of the nap. When'the coating on one side is sufficiently permeable to permit the introduction of the shrinkage material into the fabric, the coating on the other side of the fabric may be substantially impervious to the shrinking agent.

A residual shrinking of about 0.3% to about 0.5% is satisfactory for most coated fabrics but more or less shrinkage can be imparted to the material if desired. For the sake of economy, the described treatment may be carried on until the shrinkage does not exceed the indicated maximum but by further treatments, the shrinkage can be reduced practically to zero.

It is apparent that the process requires the coating material to be substantially insoluble or not deleteriously affected by the moistening agent which is used to shrink the fabric base. With this provision, the invention is not restricted to any type or formula of coated material or to any particular kind of liquid for shrinking the fabric. Consequently, a large variety of materials can be used for these purposes. Coating materials of various degrees of water imperviousness can be used. The invention is not restricted in its application to sheeting weave cotton fabrics since a large variety of fabrics such as ducks, twills, broken twills, drills, sateens and the like can be used. Fabrics composed of f1- bers such as wool, rayon and others respond with excellent results to the described invention. The duration of treatment and the number of treatments employed is roughly dependent on the weight of the fabric and the tolerance of residual shrinkage that will be permitted but the kind of fiber from which the fabric is made, its previous treatment, its weave and other circumstances may vary the requirements. Coated fabrics which are combined with coated or uncoated fabrics respond readily to the described process and the shrinkage of such materials can be reduced to a practical minimum with excellent results.

Instead of passing the coated fabric through a wetting medium or otherwise saturating the fabric, I may expose the coated material to a moisture laden atmosphere until the base material has become laden with moisture to a condition of more or less saturation. Any atmosphere having a higher humidity than the atmosphere in which the material is to be dried, may be used. Atmospheres of highest humidity and those containing congealed moisture are preferred. It is evident that treatments ranging from the mildest to the most drastic can be employed by employing wetting media which range from atmospheres of relatively low humidity through atmospheres saturated with the wetting agent, and atmospheres containing more or less moisture in suspension to the conditions of wetting where the material is soaked in the liquid wetting agent.

It is evident that various modifications of the described methods can be made without departing from the invention. It is to be understood that such modifications as will be apparent to those skilled in the art are within the contemplation of this invention and no limitation is intended in the annexed claim except those which are imposed by the prior art or are specifically recited.

I claim:

Process of manufacturing a shrunk coated fabric which comprises disposing a coating material on both sides of a textile fabric having a nap, the coating on at least one side being limited so that at least some of. the nap protrudes therethrough and can act as a wick to transport wetting agents into the fabric, subjecting the nap to a shrinking agent until the fabric is wetted, allowing the fabric to remain in a wet condition substantially without tension thereon whilst permitting the fabric to shrink, and finally removing the wetness.

CORNELIUS ANTHONY ALT. 

